In the past few decades, wireless communication grew exponentially along with various new services resulting in congestion of frequency spectrum. On the other hand, assigned spectrums based on old allocation in the past, such as TV bands, are being used inefficiently. As spectrum resource is limited, efficient reuse of underutilized frequency resources in assigned spectrums such as TVWS through new technologies has become important.
TV white space (TVWS) refers to the unused TV channels originally assigned to TV broadcasting. To improve the spectrum utilisation, several telecommunication regulators have opened TVWS for public use with license-exempt, and are actively promoting TVWS.
In TVWS applications, there is a need for a coordinating mechanism between primary users (including the operating TV channels and other licensed users) and WSDs to avoid interference to the primary users. This task can be undertaken by a geo-location database (GLDB). In particular, a WSD intending to access the TVWS spectrum needs to first access the GLDB to ascertain available channels based on its location. Thereafter, the WSD selects a free channel to transmit with allowed parameters such as emission power, out-of-band interference limits and so on.
The GLDB is an effective way to protect primary users, i.e. users of TV signals. However, existing GLDBs have the following shortcomings:                A pre-communication link between GLDB and the WSD is needed for the WSD to ascertain the available white space channels and the corresponding locations. Currently, this pre-communication link is provided by the Internet. In other words, a WSD (fixed or mode II device type) of a TVWS spectrum access must have internet access capability. This raises a contradiction. If a user has obtained internet access capability, why does the need the TVWS communications? This need for internet access reduces user's interest in the TVWS although other mode I WSDs could still access to TVWS via fixed or mode II WSDs without the need for Internet access.        With the interactive internet access link, there is a risk of GLDB hacking caused by illegal users.        With the need for WSDs to have internet access link to GLDB, there is a risk of WSDs being hacked through internet connection.        
Current TVWS spectrum accesses are based on GLDB, which are opened to public. However, as aforementioned, one of the fundamental drawbacks of this current approach is the need for WSDs to have the capability to inquire the database through internet access. A contradiction arises because when a pair of WSDs has the ability to access internet, there is no need for TVWS for communications.
Besides the GLDB approach, spectrum sensing and beacon transmitter are two alternative approaches that have been considered.
Spectrum sensing requires a WSD determine the availability of TV white space by listening to the spectrum either individually or collaboratively. The spectrum sensing approach suffers from hidden terminal problem. This means that if the channel from the primary user transmitter to the WSD is in deep fade or too weak, the WSD may not be able to detect the primary user and accessing the channel will result in interference to the primary user.
Beacon transmitter requires broadcast of primary users' information through beacon signals. The beacon signals can include channel occupancy information, transmission power, locations, and coverage area of the primary transmitters. However, there has been no concrete teaching on how the beacon transmitter approach can be realised. Existing methods on beacon transmitter can be classified into three categories:
Category 1: Each licensed primary transmitter broadcasts the beacon signal that contains the transmitter's own information. In this case, since the beacon signal of each transmitter only carries its own information, no connection to GLDB is required. The ability of a WSD in accessing a channel is determined by whether the WSD can hear the beacon or not.Category 2: United States Federal Communications Commission (FCC) has proposed using a beacon transmitter to broadcast the list of channels that can be used by any WSD within coverage area of the beacon transmitter. In this case, the beacon transmitter needs to be connected to a GLDB to obtain the list of available channels within its coverage area. Similar to Category 1, hear-ability is used to determine whether a WSD can access the channel or not.Category 3: A beacon transmitter is used to broadcast all licensed primary transmitters' information comprising frequency band, location and coverage area of each licensed transmitter within its coverage area using dedicated channel. A WSD needs to use its own location information together with the received beacon information to determine whether to access a channel. In this case, the WSD may need to self-compute to ascertain whether the WSD is within the coverage region of certain licensed transmitter.
The beacon approach of Category 1 and 2 relies on the WSD's hear-ability instead of calculating the geo-locations of each WSD. As such, performance of beacon approach is not reliable. The beacon approach of Category 3 uses the geo-location information, but it needs dedicated beacon transmitter which occupies additional frequency resource.
In view of the above and other issues with current internet accessing GLDB and other approaches used in TVWS spectrum access, method, apparatus and system for operating and communicating GLDB data, which at least obviate the above issues, are highly desired.